The present invention relates generally to a method and apparatus for measuring experimental quantities and, more particularly, to a method and apparatus for use in physics experiments for measuring experimental quantities, such as acceleration due to gravity, velocities, momentum, linear acceleration, period of a pendulum, motion of a spring, etc.
Prior art devices used in middle school to college level physics experiments to measure experimental quantities, such as acceleration, velocity, momentum, etc., use ticker-tape impact timing vibrators to measure the relative motion between a ticker tape and the ticker-tape vibrator. The ticker-tape vibrator employs electromagnetic principles as an energized induction coil momentarily magnitizes a strip of spring steel in the form of a blade which moves up and down in a regular manner. The blade makes contact with a carbon disc which is pressed against a strip of ticker tape. Each time the blade hits the carbon paper disk, a mark is printed on the ticker tape. If the ticker tape and ticker-tape vibrator are moved relative to one another, marks are printed on the ticker tape at regular intervals of time. Such timing vibrators can also use rotary action rather than reciprocating rectilinear motion as described.
These prior art devices have numerous drawbacks in that they can easily overheat if used for extended periods of time and produce a substantial quantity of noise. Additionally, hysteresis effects on the metal parts of the timing vibrators cause unsatisfactory experimental results. Furthermore, the carbon paper disks do not have a long service life, as they wear out quite quickly. More importantly, the impact of the blade on the ticker tape causes a drag effect therebetween with obvious adverse effects on the experimental results.
Another prior art timing device utilizes high induction coils to produce sparks which mark specially treated paper. The experimental capabilities of this device are limited by its weight and design.
The present invention is designed to overcome the above noted limitations that are attendant upon the use of the "prior art" devices, and toward this end, it contemplates the provision of a novel method and apparatus for measuring experimental quantities which utilizes a self-contained impactless timing device.
It is an object to provide such a device which produces little or no heat and may be operated for many hours without adversely affecting experimental results.
Still another object is to provide such a device which can be used with ordinary ticker tape paper and does not need specially treated paper.
A further object is to provide such a device which can be completely self contained and used in a plurality of physics experiments.
It is a general aim of the invention to provide such a device which may be readily and economically fabricated and will enjoy long life in operation.